Substrates having lotions and other coatings are well known in the art. Lotions are often in conjunction with substrates to soften the substrate. Lotions can also be used to soothe the skin when the substrate is used, for example, as a facial tissue. Examples of substrates having lotion and useful in the facial tissue art are found in U.S. Pat. No. 4,426,418, issued Jan. 17, 1984 to Coleman et al. and commonly assigned U.S. Pat. No. 4,481,243, issued Nov. 6, 1984 to Allen, the disclosure of which Allen patent is incorporated herein by reference.
However, these attempts in the art do not solve the problem of how to use the lotion to improve cleaning of the skin with the tissue. Nor do these attempts show how to clean other surfaces using a substrate treated with a lotion.
Products, such as wipes, have been developed. Certain wipes have a significant advantage over earlier prior art cleaning products for removing soiling, particularly from the perianal region. Such wipes comprise a substrate (e.g., a nonwoven or tissue) treated with a water-in-lipid emulsion. Such wipes are particularly advantageous for cleaning, especially when provided in the form of wet-like cleansing wipes used to remove perianal soils. Examples of such wipes and their manufacture are found in commonly assigned World Patent Applications WO 96/14835, published May 23, 1996, in the names of Mackey et al.; and WO 96/21505, published Jul. 18, 1996, in the name of DesMarais, the disclosures of which are incorporated herein by reference. These wipes release significant quantities of water during use for comfortable, more effective cleaning.
The lipid phase of the emulsion found in these wipes is sufficiently brittle so as to be easily disrupted by low shear contact or compression (e.g., during the wiping of the skin) to readily release this internal water phase, but sufficiently tough at elevated temperatures where the lipid is melted to avoid premature release of the water phase during the rigors of processing. The continuous lipid phase of these articles is also sufficiently stable during storage so as to prevent significant evaporation of the internal water phase. The normal tensile strength and flushability properties of these articles are not adversely affected when treated with the high internal phase inverse emulsions of the present invention. As a result, users of these articles get comfortable, efficient, moist cleaning without having to change their normal cleaning habits. This technology is readily useful for other purposes, such as cleaning hard surfaces, etc.
The cleaning process becomes easier if the emulsion is directly exposed to the surface to be cleaned. Such a wipe may comprise a substrate having one or two exposed, outwardly facing surfaces, and the emulsion disposed on one of the exposed surfaces. However, such an embodiment provides the disadvantages of imparting a tacky feel to the user, potential loss of emulsion from the surface, and difficulties in processing. In a preferred embodiment, the emulsion is disposed between two plies of the substrate to yield a laminate.
It has unexpectedly been found that a continuous coating of the emulsion on the substrate does not provide the most efficacious cleaning, particularly when it is desired to clean human skin. A discontinuous pattern of the emulsion on the substrate provides a cleaning mechanism not found in the prior art. As used herein, a discontinuous pattern of the emulsion is a pattern having regions of the substrate free of the emulsion intermediate regions of the substrate upon which the emulsion is disposed.
During cleaning, water is released from the emulsion to remove dirt from the skin. The area of the skin wetted by the water and from which dirt is removed is then wiped dry with the regions of the substrate free of the emulsion. Similar benefits occur when the wipe is used to clean other surfaces, such as window glass, countertops, sinks, porcelain and metal fixtures, walls and the like, and from other surfaces, such as carpeting or furniture.
The mechanism to transfer the water from the emulsion to the surface to be cleaned involves several steps. First, the water is released or expressed from the emulsion due to pressure imparted by the user. The pressure ruptures the emulsion, freeing the water. The water then saturates the substrate. Upon saturation, the water penetrates the substrate in the Z-direction. Excess water, which is that water in excess of the local absorbent capacity of the substrate then is transferred from the wipe to the surface.
One potential approach to the problem of providing sufficient quantities of water to saturate the substrate and transfer the water to the surface is to dispose a continuous layer of emulsion on the substrate. A continuous layer of emulsion may contain a greater quantity of water than a discontinuous layer of the emulsion. This potential approach has several drawbacks. First, a thin continuous layer of emulsion may not exceed the local capacity of the substrate. Second, excessive lipid phase in the emulsion causes a build up and may not be well received by the user and contribute to manufacturing difficulties. Third, if the amount of the emulsion becomes too great, it can be difficult to rupture the emulsion and release the water therefrom. Such difficulty occurs due to a greater quantity of the lipid phase being present. As the amount of lipid phase increases, slippage of the emulsion relative to itself occurs, rather than rupture of the emulsion. Fourth, the surface area to volume ratio is far from optimal. Finally, the cost of the wipe increases directly with the amount of emulsion provided.
Accordingly, it is an object of the present invention to provide a wipe comprising a substrate and a high internal phase inverse emulsion. It is further an object of the present invention to provide such a wipe having a discontinuous coating of the emulsion on the substrate. It is finally an object of the present invention to provide a wipe having such an emulsion disposed in a pattern that provides improved transmission of water released from the emulsion to the surface desired to be cleaned, while at the same time minimizing loss of such water from the emulsion due to evaporation.